1
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Biagioni G, Antolini N, Donelli B, Pezzè L, Smerzi A, Fattori M, Fioretti A, Gabbanini C, Inguscio M, Tanzi L, Modugno G. Measurement of the superfluid fraction of a supersolid by Josephson effect. Nature 2024; 629:773-777. [PMID: 38720083 PMCID: PMC11111407 DOI: 10.1038/s41586-024-07361-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 03/27/2024] [Indexed: 05/24/2024]
Abstract
A new class of superfluids and superconductors with spatially periodic modulation of the superfluid density is arising1-12. It might be related to the supersolid phase of matter, in which the spontaneous breaking of gauge and translational symmetries leads to a spatially modulated macroscopic wavefunction13-16. This relation was recognized only in some cases1,2,5-9 and there is the need for a universal property quantifying the differences between supersolids and ordinary matter, such as the superfluid fraction, which measures the reduction in superfluid stiffness resulting from the spatial modulation16-18. The superfluid fraction was introduced long ago16, but it has not yet been assessed experimentally. Here we demonstrate an innovative method to measure the superfluid fraction based on the Josephson effect, a ubiquitous phenomenon associated with the presence of a physical barrier between two superfluids or superconductors19, which might also be expected for supersolids20, owing to the spatial modulation. We demonstrate that individual cells of a supersolid can sustain Josephson oscillations and we show that, from the current-phase dynamics, we can derive directly the superfluid fraction. Our study of a cold-atom dipolar supersolid7 reveals a relatively large sub-unity superfluid fraction that makes realistic the study of previously unknown phenomena such as partially quantized vortices and supercurrents16-18. Our results open a new direction of research that may unify the description of all supersolid-like systems.
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Affiliation(s)
- G Biagioni
- Dipartimento di Fisica e Astronomia, Università degli studi di Firenze, Sesto Fiorentino, Italy
- CNR-INO, Sede di Pisa, Pisa, Italy
| | - N Antolini
- CNR-INO, Sede di Pisa, Pisa, Italy
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
| | - B Donelli
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
- CNR-INO, Sede di Firenze, Firenze, Italy
- Quantum Science and Technology in Arcetri (QSTAR), Firenze, Italy
- Università degli Studi di Napoli Federico II, Napoli, Italy
| | - L Pezzè
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
- CNR-INO, Sede di Firenze, Firenze, Italy
- Quantum Science and Technology in Arcetri (QSTAR), Firenze, Italy
| | - A Smerzi
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy.
- CNR-INO, Sede di Firenze, Firenze, Italy.
- Quantum Science and Technology in Arcetri (QSTAR), Firenze, Italy.
| | - M Fattori
- Dipartimento di Fisica e Astronomia, Università degli studi di Firenze, Sesto Fiorentino, Italy
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
- CNR-INO, Sede di Sesto Fiorentino, Sesto Fiorentino, Italy
| | | | | | - M Inguscio
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
- Dipartimento di Ingegneria, Università Campus Bio-Medico di Roma, Roma, Italy
| | - L Tanzi
- CNR-INO, Sede di Pisa, Pisa, Italy
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
| | - G Modugno
- Dipartimento di Fisica e Astronomia, Università degli studi di Firenze, Sesto Fiorentino, Italy.
- CNR-INO, Sede di Pisa, Pisa, Italy.
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy.
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2
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Pyykkönen VAJ, Peotta S, Törmä P. Suppression of Nonequilibrium Quasiparticle Transport in Flat-Band Superconductors. PHYSICAL REVIEW LETTERS 2023; 130:216003. [PMID: 37295081 DOI: 10.1103/physrevlett.130.216003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 04/13/2023] [Indexed: 06/12/2023]
Abstract
We study nonequilibrium transport through a superconducting flat-band lattice in a two-terminal setup with the Schwinger-Keldysh method. We find that quasiparticle transport is suppressed and coherent pair transport dominates. For superconducting leads, the ac supercurrent overcomes the dc current, which relies on multiple Andreev reflections. With normal-normal and normal-superconducting leads, the Andreev reflection and normal currents vanish. Flat-band superconductivity is, thus, promising not only for high critical temperatures, but also for suppressing unwanted quasiparticle processes.
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Affiliation(s)
- Ville A J Pyykkönen
- Department of Applied Physics, Aalto University School of Science, FI-00076 Aalto, Finland
| | - Sebastiano Peotta
- Department of Applied Physics, Aalto University School of Science, FI-00076 Aalto, Finland
| | - Päivi Törmä
- Department of Applied Physics, Aalto University School of Science, FI-00076 Aalto, Finland
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3
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Huang MZ, Mohan J, Visuri AM, Fabritius P, Talebi M, Wili S, Uchino S, Giamarchi T, Esslinger T. Superfluid Signatures in a Dissipative Quantum Point Contact. PHYSICAL REVIEW LETTERS 2023; 130:200404. [PMID: 37267563 DOI: 10.1103/physrevlett.130.200404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 02/13/2023] [Accepted: 04/13/2023] [Indexed: 06/04/2023]
Abstract
We measure superfluid transport of strongly interacting fermionic lithium atoms through a quantum point contact with local, spin-dependent particle loss. We observe that the characteristic non-Ohmic superfluid transport enabled by high-order multiple Andreev reflections transitions into an excess Ohmic current as the dissipation strength exceeds the superfluid gap. We develop a model with mean-field reservoirs connected via tunneling to a dissipative site. Our calculations in the Keldysh formalism reproduce the observed nonequilibrium particle current, yet do not fully explain the observed loss rate or spin current.
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Affiliation(s)
- Meng-Zi Huang
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - Jeffrey Mohan
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - Anne-Maria Visuri
- Physikalisches Institut, University of Bonn, Nussallee 12, 53115 Bonn, Germany
| | - Philipp Fabritius
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - Mohsen Talebi
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - Simon Wili
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - Shun Uchino
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
| | - Thierry Giamarchi
- Department of Quantum Matter Physics, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - Tilman Esslinger
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
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4
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Wlazłowski G, Xhani K, Tylutki M, Proukakis NP, Magierski P. Dissipation Mechanisms in Fermionic Josephson Junction. PHYSICAL REVIEW LETTERS 2023; 130:023003. [PMID: 36706420 DOI: 10.1103/physrevlett.130.023003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/10/2022] [Accepted: 12/12/2022] [Indexed: 06/18/2023]
Abstract
We characterize numerically the dominant dynamical regimes in a superfluid ultracold fermionic Josephson junction. Beyond the coherent Josephson plasma regime, we discuss the onset and physical mechanism of dissipation due to the superflow exceeding a characteristic speed, and provide clear evidence distinguishing its physical mechanism across the weakly and strongly interacting limits, despite qualitative dynamics of global characteristics being only weakly sensitive to the operating dissipative mechanism. Specifically, dissipation in the strongly interacting regime occurs through the phase-slippage process, caused by the emission and propagation of quantum vortices, and sound waves-similar to the Bose-Einstein condensation limit. Instead, in the weak interaction limit, the main dissipative channel arises through the pair-breaking mechanism.
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Affiliation(s)
- Gabriel Wlazłowski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Klejdja Xhani
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - Marek Tylutki
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, Poland
| | - Nikolaos P Proukakis
- Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Piotr Magierski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
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5
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Cai Y, Allman DG, Sabharwal P, Wright KC. Persistent Currents in Rings of Ultracold Fermionic Atoms. PHYSICAL REVIEW LETTERS 2022; 128:150401. [PMID: 35499879 DOI: 10.1103/physrevlett.128.150401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 12/31/2021] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
We have produced persistent currents of ultracold fermionic atoms trapped in a ring, with lifetimes greater than 10 sec in the strongly interacting regime. These currents remain stable well into the BCS regime at sufficiently low temperature. We drive a circulating BCS superfluid into the normal phase and back by changing the interaction strength and find that the probability for quantized superflow to reappear is remarkably insensitive to the time spent in the normal phase and the minimum interaction strength. After ruling out spontaneous current formation for our experimental conditions, we argue that the reappearance of superflow is due to weak damping of normal currents in this limit. These results establish that ultracold fermionic atoms with tunable interactions can be used to create matter-wave circuits similar to those previously created with weakly interacting bosonic atoms.
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Affiliation(s)
- Yanping Cai
- Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755, USA
| | - Daniel G Allman
- Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755, USA
| | - Parth Sabharwal
- Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755, USA
| | - Kevin C Wright
- Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755, USA
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6
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An FA, Sundar B, Hou J, Luo XW, Meier EJ, Zhang C, Hazzard KRA, Gadway B. Nonlinear Dynamics in a Synthetic Momentum-State Lattice. PHYSICAL REVIEW LETTERS 2021; 127:130401. [PMID: 34623847 DOI: 10.1103/physrevlett.127.130401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
The scope of analog simulation in atomic, molecular, and optical systems has expanded greatly over the past decades. Recently, the idea of synthetic dimensions-in which transport occurs in a space spanned by internal or motional states coupled by field-driven transitions-has played a key role in this expansion. While approaches based on synthetic dimensions have led to rapid advances in single-particle Hamiltonian engineering, strong interaction effects have been conspicuously absent from most synthetic dimensions platforms. Here, in a lattice of coupled atomic momentum states, we show that atomic interactions result in large and qualitative changes to dynamics in the synthetic dimension. We explore how the interplay of nonlinear interactions and coherent tunneling enriches the dynamics of a one-band tight-binding model giving rise to macroscopic self-trapping and phase-driven Josephson dynamics with a nonsinusoidal current-phase relationship, which can be viewed as stemming from a nonlinear band structure arising from interactions.
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Affiliation(s)
- Fangzhao Alex An
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Bhuvanesh Sundar
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
- JILA, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Junpeng Hou
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA
| | - Xi-Wang Luo
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA
| | - Eric J Meier
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Chuanwei Zhang
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA
| | - Kaden R A Hazzard
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Bryce Gadway
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
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7
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Yamamoto K, Nakagawa M, Tsuji N, Ueda M, Kawakami N. Collective Excitations and Nonequilibrium Phase Transition in Dissipative Fermionic Superfluids. PHYSICAL REVIEW LETTERS 2021; 127:055301. [PMID: 34397242 DOI: 10.1103/physrevlett.127.055301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 06/17/2021] [Indexed: 06/13/2023]
Abstract
We predict a new mechanism to induce collective excitations and a nonequilibrium phase transition of fermionic superfluids via a sudden switch on of two-body loss, for which we extend the BCS theory to fully incorporate a change in particle number. We find that a sudden switch on of dissipation induces an amplitude oscillation of the superfluid order parameter accompanied by a chirped phase rotation as a consequence of particle loss. We demonstrate that when dissipation is introduced to one of the two superfluids coupled via a Josephson junction, it gives rise to a nonequilibrium dynamical phase transition characterized by the vanishing dc Josephson current. The dissipation-induced collective modes and nonequilibrium phase transition can be realized with ultracold fermionic atoms subject to inelastic collisions.
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Affiliation(s)
- Kazuki Yamamoto
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Masaya Nakagawa
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
| | - Naoto Tsuji
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Masahito Ueda
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Institute for Physics of Intelligence, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
| | - Norio Kawakami
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
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8
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Del Pace G, Kwon WJ, Zaccanti M, Roati G, Scazza F. Tunneling Transport of Unitary Fermions across the Superfluid Transition. PHYSICAL REVIEW LETTERS 2021; 126:055301. [PMID: 33605753 DOI: 10.1103/physrevlett.126.055301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
We investigate the transport of a Fermi gas with unitarity-limited interactions across the superfluid phase transition, probing its response to a direct current (dc) drive through a tunnel junction. As the superfluid critical temperature is crossed from below, we observe the evolution from a highly nonlinear to an Ohmic conduction characteristic, associated with the critical breakdown of the Josephson dc current induced by pair condensate depletion. Moreover, we reveal a large and dominant anomalous contribution to resistive currents, which reaches its maximum at the lowest attained temperature, fostered by the tunnel coupling between the condensate and phononic Bogoliubov-Anderson excitations. Increasing the temperature, while the zeroing of supercurrents marks the transition to the normal phase, the conductance drops considerably but remains much larger than that of a normal, uncorrelated Fermi gas tunneling through the same junction. We attribute such enhanced transport to incoherent tunneling of sound modes, which remain weakly damped in the collisional hydrodynamic fluid of unpaired fermions at unitarity.
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Affiliation(s)
- G Del Pace
- Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino, Italy
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - W J Kwon
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - M Zaccanti
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - G Roati
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - F Scazza
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
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9
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Autti S, Heikkinen PJ, Mäkinen JT, Volovik GE, Zavjalov VV, Eltsov VB. AC Josephson effect between two superfluid time crystals. NATURE MATERIALS 2021; 20:171-174. [PMID: 32807922 DOI: 10.1038/s41563-020-0780-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 07/22/2020] [Indexed: 06/11/2023]
Abstract
Quantum time crystals are systems characterized by spontaneously emerging periodic order in the time domain1. While originally a phase of broken time translation symmetry was a mere speculation2, a wide range of time crystals has been reported3-5. However, the dynamics and interactions between such systems have not been investigated experimentally. Here we study two adjacent quantum time crystals realized by two magnon condensates in superfluid 3He-B. We observe an exchange of magnons between the time crystals leading to opposite-phase oscillations in their populations-a signature of the AC Josephson effect6-while the defining periodic motion remains phase coherent throughout the experiment. Our results demonstrate that time crystals obey the general dynamics of quantum mechanics and offer a basis to further investigate the fundamental properties of these phases, opening pathways for possible applications in developing fields, such as quantum information processing.
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Affiliation(s)
- S Autti
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland.
- Department of Physics, Lancaster University, Lancaster, UK.
| | - P J Heikkinen
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
- Department of Physics, Royal Holloway, University of London, Egham, UK
| | - J T Mäkinen
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
- Department of Physics, Yale University, New Haven, CT, USA
- Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - G E Volovik
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
- L.D. Landau Institute for Theoretical Physics, Moscow, Russia
| | - V V Zavjalov
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
- Department of Physics, Lancaster University, Lancaster, UK
| | - V B Eltsov
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland.
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10
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Patel PB, Yan Z, Mukherjee B, Fletcher RJ, Struck J, Zwierlein MW. Universal sound diffusion in a strongly interacting Fermi gas. Science 2021; 370:1222-1226. [PMID: 33273102 DOI: 10.1126/science.aaz5756] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 10/24/2020] [Indexed: 11/02/2022]
Abstract
Transport of strongly interacting fermions is crucial for the properties of modern materials, nuclear fission, the merging of neutron stars, and the expansion of the early Universe. Here, we observe a universal quantum limit of diffusivity in a homogeneous, strongly interacting atomic Fermi gas by studying sound propagation and its attenuation through the coupled transport of momentum and heat. In the normal state, the sound diffusivity D monotonically decreases upon lowering the temperature, in contrast to the diverging behavior of weakly interacting Fermi liquids. Below the superfluid transition temperature, D attains a universal value set by the ratio of Planck's constant and the particle mass. Our findings inform theories of fermion transport, with relevance for hydrodynamic flow of electrons, neutrons, and quarks.
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Affiliation(s)
- Parth B Patel
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zhenjie Yan
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Biswaroop Mukherjee
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Richard J Fletcher
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Julian Struck
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Département de Physique, Ecole Normale Supérieure/PSL Research University, CNRS, 24 rue Lhomond, 75005 Paris, France
| | - Martin W Zwierlein
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. .,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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11
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Kwon WJ, Del Pace G, Panza R, Inguscio M, Zwerger W, Zaccanti M, Scazza F, Roati G. Strongly correlated superfluid order parameters from dc Josephson supercurrents. Science 2020; 369:84-88. [DOI: 10.1126/science.aaz2463] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 04/27/2020] [Indexed: 11/02/2022]
Affiliation(s)
- W. J. Kwon
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
| | - G. Del Pace
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino, Italy
| | - R. Panza
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
| | - M. Inguscio
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
- Department of Engineering, Campus Bio-Medico University of Rome, 00128 Rome, Italy
| | - W. Zwerger
- Physics Department, Technische Universität München, 85747 Garching, Germany
| | - M. Zaccanti
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
| | - F. Scazza
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
| | - G. Roati
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
- European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
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12
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Luick N, Sobirey L, Bohlen M, Singh VP, Mathey L, Lompe T, Moritz H. An ideal Josephson junction in an ultracold two-dimensional Fermi gas. Science 2020; 369:89-91. [DOI: 10.1126/science.aaz2342] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 05/07/2020] [Indexed: 11/02/2022]
Affiliation(s)
- Niclas Luick
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Lennart Sobirey
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Markus Bohlen
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 24 rue Lhomond, 75005 Paris, France
| | - Vijay Pal Singh
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Ludwig Mathey
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Thomas Lompe
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Henning Moritz
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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13
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Xhani K, Neri E, Galantucci L, Scazza F, Burchianti A, Lee KL, Barenghi CF, Trombettoni A, Inguscio M, Zaccanti M, Roati G, Proukakis NP. Critical Transport and Vortex Dynamics in a Thin Atomic Josephson Junction. PHYSICAL REVIEW LETTERS 2020; 124:045301. [PMID: 32058733 DOI: 10.1103/physrevlett.124.045301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Indexed: 06/10/2023]
Abstract
We study the onset of dissipation in an atomic Josephson junction between Fermi superfluids in the molecular Bose-Einstein condensation limit of strong attraction. Our simulations identify the critical population imbalance and the maximum Josephson current delimiting dissipationless and dissipative transport, in quantitative agreement with recent experiments. We unambiguously link dissipation to vortex ring nucleation and dynamics, demonstrating that quantum phase slips are responsible for the observed resistive current. Our work directly connects microscopic features with macroscopic dissipative transport, providing a comprehensive description of vortex ring dynamics in three-dimensional inhomogeneous constricted superfluids at zero and finite temperatures.
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Affiliation(s)
- K Xhani
- Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
- European Laboratory for Non-Linear Spectroscopy (LENS), Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - E Neri
- Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - L Galantucci
- Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - F Scazza
- European Laboratory for Non-Linear Spectroscopy (LENS), Università di Firenze, 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - A Burchianti
- European Laboratory for Non-Linear Spectroscopy (LENS), Università di Firenze, 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - K-L Lee
- Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - C F Barenghi
- Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - A Trombettoni
- CNR-IOM DEMOCRITOS Simulation Center and SISSA, Via Bonomea 265, I-34136 Trieste, Italy
| | - M Inguscio
- European Laboratory for Non-Linear Spectroscopy (LENS), Università di Firenze, 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
- Department of Engineering, Campus Bio-Medico University of Rome, 00128 Rome, Italy
| | - M Zaccanti
- European Laboratory for Non-Linear Spectroscopy (LENS), Università di Firenze, 50019 Sesto Fiorentino, Italy
- Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - G Roati
- European Laboratory for Non-Linear Spectroscopy (LENS), Università di Firenze, 50019 Sesto Fiorentino, Italy
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - N P Proukakis
- Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
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14
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Gauthier G, Szigeti SS, Reeves MT, Baker M, Bell TA, Rubinsztein-Dunlop H, Davis MJ, Neely TW. Quantitative Acoustic Models for Superfluid Circuits. PHYSICAL REVIEW LETTERS 2019; 123:260402. [PMID: 31951434 DOI: 10.1103/physrevlett.123.260402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Indexed: 06/10/2023]
Abstract
We experimentally realize a highly tunable superfluid oscillator circuit in a quantum gas of ultracold atoms and develop and verify a simple lumped-element description of this circuit. At low oscillator currents, we demonstrate that the circuit is accurately described as a Helmholtz resonator, a fundamental element of acoustic circuits. At larger currents, the breakdown of the Helmholtz regime is heralded by a turbulent shedding of vortices and density waves. Although a simple phase-slip model offers qualitative insights into the circuit's resistive behavior, our results indicate deviations from the phase-slip model. A full understanding of the dissipation in superfluid circuits will thus require the development of empirical models of the turbulent dynamics in this system, as have been developed for classical acoustic systems.
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Affiliation(s)
- Guillaume Gauthier
- ARC Centre of Excellence for Engineered Quantum Systems, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - Stuart S Szigeti
- ARC Centre of Excellence for Engineered Quantum Systems, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
- Department of Quantum Science, Research School of Physics, The Australian National University, Canberra 2601, Australia
| | - Matthew T Reeves
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - Mark Baker
- ARC Centre of Excellence for Engineered Quantum Systems, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - Thomas A Bell
- ARC Centre of Excellence for Engineered Quantum Systems, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - Halina Rubinsztein-Dunlop
- ARC Centre of Excellence for Engineered Quantum Systems, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - Matthew J Davis
- ARC Centre of Excellence for Engineered Quantum Systems, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - Tyler W Neely
- ARC Centre of Excellence for Engineered Quantum Systems, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
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15
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Bighin G, Defenu N, Nándori I, Salasnich L, Trombettoni A. Berezinskii-Kosterlitz-Thouless Paired Phase in Coupled XY Models. PHYSICAL REVIEW LETTERS 2019; 123:100601. [PMID: 31573277 DOI: 10.1103/physrevlett.123.100601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Indexed: 06/10/2023]
Abstract
We study the effect of a linear tunneling coupling between two-dimensional systems, each separately exhibiting the topological Berezinskii-Kosterlitz-Thouless (BKT) transition. In the uncoupled limit, there are two phases: one where the one-body correlation functions are algebraically decaying and the other with exponential decay. When the linear coupling is turned on, a third BKT-paired phase emerges, in which one-body correlations are exponentially decaying, while two-body correlation functions exhibit power-law decay. We perform numerical simulations in the paradigmatic case of two coupled XY models at finite temperature, finding evidences that for any finite value of the interlayer coupling, the BKT-paired phase is present. We provide a picture of the phase diagram using a renormalization group approach.
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Affiliation(s)
- Giacomo Bighin
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Nicolò Defenu
- Institut für Theoretische Physik, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - István Nándori
- MTA-DE Particle Physics Research Group, P.O.Box 51, H-4001 Debrecen, Hungary
- MTA Atomki, P.O.Box 51, H-4001 Debrecen, Hungary
- University of Debrecen, P.O.Box 105, H-4010 Debrecen, Hungary
| | - Luca Salasnich
- Dipartimento di Fisica e Astronomia "Galileo Galilei," Università di Padova, Via Marzolo 8, 35131 Padova, Italy
- Istituto Nazionale di Ottica (INO) del Consiglio Nazionale delle Ricerche (CNR), Sezione di Sesto Fiorentino, Via Nello Carrara 2, 50019 Sesto Fiorentino, Italy
| | - Andrea Trombettoni
- CNR-IOM DEMOCRITOS Simulation Center, Via Bonomea 265, I-34136 Trieste, Italy
- SISSA and INFN, Sezione di Trieste, Via Bonomea 265, I-34136 Trieste, Italy
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16
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Mumford J, Turner E, Sprung DWL, O'Dell DHJ. Quantum Spin Dynamics in Fock Space Following Quenches: Caustics and Vortices. PHYSICAL REVIEW LETTERS 2019; 122:170402. [PMID: 31107066 DOI: 10.1103/physrevlett.122.170402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 08/22/2018] [Indexed: 06/09/2023]
Abstract
Caustics occur widely in dynamics and take on shapes classified by catastrophe theory. At finite wavelengths they produce interference patterns containing networks of vortices (phase singularities). Here we investigate caustics in quantized fields, focusing on the collective dynamics of quantum spins. We show that, following a quench, caustics are generated in the Fock space amplitudes specifying the many-body configuration and which are accessible in experiments with cold atoms, ions, or photons. The granularity of quantum fields removes all singularities, including phase singularities, converting point vortices into nonlocal vortices that annihilate in pairs as the quantization scale is increased. Furthermore, the continuous scaling laws of wave catastrophes are replaced by discrete versions. Such "quantum catastrophes" are expected to be universal dynamical features of quantized fields.
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Affiliation(s)
- J Mumford
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W., Hamilton, Ontario, L8S 4M1, Canada
| | - E Turner
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W., Hamilton, Ontario, L8S 4M1, Canada
| | - D W L Sprung
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W., Hamilton, Ontario, L8S 4M1, Canada
| | - D H J O'Dell
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W., Hamilton, Ontario, L8S 4M1, Canada
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17
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Brown PT, Mitra D, Guardado-Sanchez E, Nourafkan R, Reymbaut A, Hébert CD, Bergeron S, Tremblay AMS, Kokalj J, Huse DA, Schauß P, Bakr WS. Bad metallic transport in a cold atom Fermi-Hubbard system. Science 2018; 363:379-382. [PMID: 30523078 DOI: 10.1126/science.aat4134] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 10/30/2018] [Indexed: 11/03/2022]
Abstract
Strong interactions in many-body quantum systems complicate the interpretation of charge transport in such materials. To shed light on this problem, we study transport in a clean quantum system: ultracold lithium-6 in a two-dimensional optical lattice, a testing ground for strong interaction physics in the Fermi-Hubbard model. We determine the diffusion constant by measuring the relaxation of an imposed density modulation and modeling its decay hydrodynamically. The diffusion constant is converted to a resistivity by using the Nernst-Einstein relation. That resistivity exhibits a linear temperature dependence and shows no evidence of saturation, two characteristic signatures of a bad metal. The techniques we developed in this study may be applied to measurements of other transport quantities, including the optical conductivity and thermopower.
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Affiliation(s)
- Peter T Brown
- Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Debayan Mitra
- Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | | | - Reza Nourafkan
- Département de Physique, Institut Quantique, and Regroupement Québécois sur les Matériaux de Pointe, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Alexis Reymbaut
- Département de Physique, Institut Quantique, and Regroupement Québécois sur les Matériaux de Pointe, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Charles-David Hébert
- Département de Physique, Institut Quantique, and Regroupement Québécois sur les Matériaux de Pointe, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Simon Bergeron
- Département de Physique, Institut Quantique, and Regroupement Québécois sur les Matériaux de Pointe, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - A-M S Tremblay
- Département de Physique, Institut Quantique, and Regroupement Québécois sur les Matériaux de Pointe, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada.,Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Jure Kokalj
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia.,Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - David A Huse
- Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Peter Schauß
- Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Waseem S Bakr
- Department of Physics, Princeton University, Princeton, NJ 08544, USA.
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18
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Park JW, Ko B, Shin Y. Critical Vortex Shedding in a Strongly Interacting Fermionic Superfluid. PHYSICAL REVIEW LETTERS 2018; 121:225301. [PMID: 30547641 DOI: 10.1103/physrevlett.121.225301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Indexed: 06/09/2023]
Abstract
We study the critical vortex shedding in a strongly interacting fermionic superfluid of ^{6}Li across the BEC-BCS crossover. By moving an optical obstacle in the sample and directly imaging the vortices after the time of flight, the critical velocity u_{vor} for vortex shedding is measured as a function of the obstacle travel distance L. The observed u_{vor} increases with decreasing L, where the rate of increase is the highest in the unitary regime. In the deep Bose-Einstein condensation regime, an empirical dissipation model well captures the dependence of u_{vor} on L, characterized by a constant value of η=-[d(1/u_{vor})/d(1/L)]. However, as the system is tuned across the resonance, a step increase of η develops about a characteristic distance L_{c} as L is increased, where L_{c} is comparable to the obstacle size. This bimodal behavior is strengthened as the system is tuned towards the BCS regime. We attribute this evolution of u_{vor} to the emergence of the underlying fermionic degree of freedom in the vortex-shedding dynamics of a Fermi condensate.
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Affiliation(s)
- Jee Woo Park
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
| | - Bumsuk Ko
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
| | - Y Shin
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
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19
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Scherg S, Kohlert T, Herbrych J, Stolpp J, Bordia P, Schneider U, Heidrich-Meisner F, Bloch I, Aidelsburger M. Nonequilibrium Mass Transport in the 1D Fermi-Hubbard Model. PHYSICAL REVIEW LETTERS 2018; 121:130402. [PMID: 30312049 DOI: 10.1103/physrevlett.121.130402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/21/2018] [Indexed: 06/08/2023]
Abstract
We experimentally and numerically investigate the sudden expansion of fermions in a homogeneous one-dimensional optical lattice. For initial states with an appreciable amount of doublons, we observe a dynamical phase separation between rapidly expanding singlons and slow doublons remaining in the trap center, realizing the key aspect of fermionic quantum distillation in the strongly interacting limit. For initial states without doublons, we find a reduced interaction dependence of the asymptotic expansion speed compared to bosons, which is explained by the interaction energy produced in the quench.
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Affiliation(s)
- S Scherg
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - T Kohlert
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - J Herbrych
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J Stolpp
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
- Institute for Theoretical Physics, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
- Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, 80333 Munich, Germany
| | - P Bordia
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - U Schneider
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - F Heidrich-Meisner
- Institute for Theoretical Physics, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - I Bloch
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - M Aidelsburger
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
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20
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Rossi R, Ohgoe T, Van Houcke K, Werner F. Resummation of Diagrammatic Series with Zero Convergence Radius for Strongly Correlated Fermions. PHYSICAL REVIEW LETTERS 2018; 121:130405. [PMID: 30312043 DOI: 10.1103/physrevlett.121.130405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 07/26/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate that a summing up series of Feynman diagrams can yield unbiased accurate results for strongly correlated fermions even when the convergence radius vanishes. We consider the unitary Fermi gas, a model of nonrelativistic fermions in three-dimensional continuous space. Diagrams are built from partially dressed or fully dressed propagators of single particles and pairs. The series is resummed by a conformal-Borel transformation that incorporates the large-order behavior and the analytic structure in the Borel plane, which are found by the instanton approach. We report highly accurate numerical results for the equation of state in the normal unpolarized regime, and reconcile experimental data with the theoretically conjectured fourth virial coefficient.
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Affiliation(s)
- R Rossi
- Laboratoire de Physique Statistique, Ecole Normale Supérieure-Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, 75005 Paris, France
| | - T Ohgoe
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - K Van Houcke
- Laboratoire de Physique Statistique, Ecole Normale Supérieure-Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, 75005 Paris, France
| | - F Werner
- Laboratoire Kastler Brossel, Ecole Normale Supérieure-Université PSL, CNRS, Sorbonne Université, Collège de France, 75005 Paris, France
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21
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Gänger B, Phieler J, Nagler B, Widera A. A versatile apparatus for fermionic lithium quantum gases based on an interference-filter laser system. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:093105. [PMID: 30278689 DOI: 10.1063/1.5045827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/25/2018] [Indexed: 06/08/2023]
Abstract
We report on the design and construction of a versatile setup for experiments with ultracold lithium (Li) gases. We discuss our methods to prepare an atomic beam and laser cool it in a Zeeman slower and a subsequent magneto-optical trap, which rely on established methods. We focus on our laser system based on a stable interference-filter-stabilized, linear-extended-cavity diode laser, so far unreported for lithium wavelengths. Moreover, we describe our optical setup to combine various laser frequencies for cooling, manipulation, and detection of Li atoms. We characterize the performance of our system preparing degenerate samples of Li atoms via forced evaporation in a hybrid crossed-beam optical-dipole trap plus confining magnetic trap. Our apparatus allows one to produce quantum gases of N ≈ 105…106 fermionic lithium-6 atoms at nanokelvin temperatures in cycle times below 10 s. Our optical system is particularly suited to study the dynamics of fermionic superfluids in engineered optical potentials.
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Affiliation(s)
- Benjamin Gänger
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jan Phieler
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Benjamin Nagler
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Artur Widera
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
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22
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Polo J, Ahufinger V, Hekking FWJ, Minguzzi A. Damping of Josephson Oscillations in Strongly Correlated One-Dimensional Atomic Gases. PHYSICAL REVIEW LETTERS 2018; 121:090404. [PMID: 30230871 DOI: 10.1103/physrevlett.121.090404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Indexed: 06/08/2023]
Abstract
We study Josephson oscillations of two strongly correlated one-dimensional bosonic clouds separated by a localized barrier. Using a quantum-Langevin approach and the exact Tonks-Girardeau solution in the impenetrable-boson limit, we determine the dynamical evolution of the particle-number imbalance, displaying an effective damping of the Josephson oscillations which depends on barrier height, interaction strength, and temperature. We show that the damping originates from the quantum and thermal fluctuations intrinsically present in the strongly correlated gas. Because of the density-phase duality of the model, the same results apply to particle-current oscillations in a one-dimensional ring where a weak barrier couples different angular momentum states.
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Affiliation(s)
- J Polo
- Univ. Grenoble Alpes, CNRS, LPMMC, F-38000 Grenoble, France
| | - V Ahufinger
- Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
| | - F W J Hekking
- Univ. Grenoble Alpes, CNRS, LPMMC, F-38000 Grenoble, France
| | - A Minguzzi
- Univ. Grenoble Alpes, CNRS, LPMMC, F-38000 Grenoble, France
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23
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Abstract
We report on coupled heat and particle transport measurements through a quantum point contact (QPC) connecting two reservoirs of resonantly interacting, finite temperature Fermi gases. After heating one of them, we observe a particle current flowing from cold to hot. We monitor the temperature evolution of the reservoirs and find that the system evolves after an initial response into a nonequilibrium steady state with finite temperature and chemical potential differences across the QPC. In this state any relaxation in the form of heat and particle currents vanishes. From our measurements we extract the transport coefficients of the QPC and deduce a Lorenz number violating the Wiedemann-Franz law by one order of magnitude, a characteristic persisting even for a wide contact. In contrast, the Seebeck coefficient takes a value close to that expected for a noninteracting Fermi gas and shows a smooth decrease as the atom density close to the QPC is increased beyond the superfluid transition. Our work represents a fermionic analog of the fountain effect observed with superfluid helium and poses challenges for microscopic modeling of the finite temperature dynamics of the unitary Fermi gas.
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24
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Hou J, Luo XW, Sun K, Bersano T, Gokhroo V, Mossman S, Engels P, Zhang C. Momentum-Space Josephson Effects. PHYSICAL REVIEW LETTERS 2018; 120:120401. [PMID: 29694081 DOI: 10.1103/physrevlett.120.120401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Indexed: 06/08/2023]
Abstract
The Josephson effect is a prominent phenomenon of quantum supercurrents that has been widely studied in superconductors and superfluids. Typical Josephson junctions consist of two real-space superconductors (superfluids) coupled through a weak tunneling barrier. Here we propose a momentum-space Josephson junction in a spin-orbit coupled Bose-Einstein condensate, where states with two different momenta are coupled through Raman-assisted tunneling. We show that Josephson currents can be induced not only by applying the equivalent of "voltages," but also by tuning tunneling phases. Such tunneling-phase-driven Josephson junctions in momentum space are characterized through both full mean field analysis and a concise two-level model, demonstrating the important role of interactions between atoms. Our scheme provides a platform for experimentally realizing momentum-space Josephson junctions and exploring their applications in quantum-mechanical circuits.
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Affiliation(s)
- Junpeng Hou
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA
| | - Xi-Wang Luo
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA
| | - Kuei Sun
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA
| | - Thomas Bersano
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA
| | - Vandna Gokhroo
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA
| | - Sean Mossman
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA
| | - Peter Engels
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA
| | - Chuanwei Zhang
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA
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25
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Ground-State Magnetization in Mixtures of a Few Ultra-Cold Fermions in One-Dimensional Traps. CONDENSED MATTER 2018. [DOI: 10.3390/condmat3010007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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26
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Burchianti A, Scazza F, Amico A, Valtolina G, Seman JA, Fort C, Zaccanti M, Inguscio M, Roati G. Connecting Dissipation and Phase Slips in a Josephson Junction between Fermionic Superfluids. PHYSICAL REVIEW LETTERS 2018; 120:025302. [PMID: 29376686 DOI: 10.1103/physrevlett.120.025302] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Indexed: 06/07/2023]
Abstract
We study the emergence of dissipation in an atomic Josephson junction between weakly coupled superfluid Fermi gases. We find that vortex-induced phase slippage is the dominant microscopic source of dissipation across the Bose-Einstein condensate-Bardeen-Cooper-Schrieffer crossover. We explore different dynamical regimes by tuning the bias chemical potential between the two superfluid reservoirs. For small excitations, we observe dissipation and phase coherence to coexist, with a resistive current followed by well-defined Josephson oscillations. We link the junction transport properties to the phase-slippage mechanism, finding that vortex nucleation is primarily responsible for the observed trends of conductance and critical current. For large excitations, we observe the irreversible loss of coherence between the two superfluids, and transport cannot be described only within an uncorrelated phase-slip picture. Our findings open new directions for investigating the interplay between dissipative and superfluid transport in strongly correlated Fermi systems, and general concepts in out-of-equilibrium quantum systems.
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Affiliation(s)
- A Burchianti
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), 50019 Sesto Fiorentino, Italy
- LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - F Scazza
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), 50019 Sesto Fiorentino, Italy
- LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - A Amico
- LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - G Valtolina
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), 50019 Sesto Fiorentino, Italy
- LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - J A Seman
- Instituto de Fisica, Universidad Nacional Autónoma de México, 01000 Ciudad de México, Mexico
| | - C Fort
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), 50019 Sesto Fiorentino, Italy
- LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - M Zaccanti
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), 50019 Sesto Fiorentino, Italy
- LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - M Inguscio
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), 50019 Sesto Fiorentino, Italy
- LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - G Roati
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), 50019 Sesto Fiorentino, Italy
- LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
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Sekizawa K, Wlazłowski G, Magierski P. Solitonic excitations in collisions of superfluid nuclei a qualitatively new phenomenon distinct from the Josephson effect. EPJ WEB OF CONFERENCES 2017. [DOI: 10.1051/epjconf/201716300051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Krinner S, Esslinger T, Brantut JP. Two-terminal transport measurements with cold atoms. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:343003. [PMID: 28749788 DOI: 10.1088/1361-648x/aa74a1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In recent years, the ability of cold atom experiments to explore condensed-matter-related questions has dramatically progressed. Transport experiments, in particular, have expanded to the point in which conductance and other transport coefficients can now be measured in a way that is directly analogous to solid-state physics, extending cold-atom-based quantum simulations into the domain of quantum electronic devices. In this topical review, we describe the transport experiments performed with cold gases in the two-terminal configuration, with an emphasis on the specific features of cold atomic gases compared to solid-state physics. We present the experimental techniques and the main experimental findings, focusing on-but not restricted to-the recent experiments performed by our group. We finally discuss the perspectives opened up by this approach, the main technical and conceptual challenges for future developments, and potential applications in quantum simulation for transport phenomena and mesoscopic physics problems.
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Affiliation(s)
- Sebastian Krinner
- Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland
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Häusler S, Nakajima S, Lebrat M, Husmann D, Krinner S, Esslinger T, Brantut JP. Scanning Gate Microscope for Cold Atomic Gases. PHYSICAL REVIEW LETTERS 2017; 119:030403. [PMID: 28777599 DOI: 10.1103/physrevlett.119.030403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Indexed: 06/07/2023]
Abstract
We present a scanning probe microscopy technique for spatially resolving transport in cold atomic gases, in close analogy with scanning gate microscopy in semiconductor physics. The conductance of a quantum point contact connected to two atomic reservoirs is measured in the presence of a tightly focused laser beam acting as a local perturbation that can be precisely positioned in space. By scanning its position and recording the subsequent variations of conductance, we retrieve a high-resolution map of transport through a quantum point contact. We demonstrate a spatial resolution comparable to the extent of the transverse wave function of the atoms inside the channel and a position sensitivity below 10 nm. Our measurements agree well with an analytical model and ab initio numerical simulations, allowing us to identify a regime in transport where tunneling dominates over thermal effects. Our technique opens new perspectives for the high-resolution observation and manipulation of cold atomic gases.
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Affiliation(s)
- Samuel Häusler
- Department of Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Shuta Nakajima
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Martin Lebrat
- Department of Physics, ETH Zurich, 8093 Zurich, Switzerland
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Non-equilibrium 8π Josephson effect in atomic Kitaev wires. Nat Commun 2016; 7:12280. [PMID: 27481540 PMCID: PMC4974643 DOI: 10.1038/ncomms12280] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/17/2016] [Indexed: 11/08/2022] Open
Abstract
The identification of fractionalized excitations, such as Majorana quasi-particles, would be a striking signal of the realization of exotic quantum states of matter. While the paramount demonstration of such excitations would be a probe of their non-Abelian statistics via controlled braiding operations, alternative proposals exist that may be easier to access experimentally. Here we identify a signature of Majorana quasi-particles, qualitatively different from the behaviour of a conventional superconductor, which can be detected in cold atom systems using alkaline-earth-like atoms. The system studied is a Kitaev wire interrupted by an extra site, which gives rise to super-exchange coupling between two Majorana-bound states. We show that this system hosts a tunable, non-equilibrium Josephson effect with a characteristic 8π periodicity of the Josephson current. The visibility of the 8π periodicity of the Josephson current is then studied including the effects of dephasing and particle losses.
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Nolli R, Venturelli M, Marmugi L, Wickenbrock A, Renzoni F. Compact setup for the production of (87)Rb |F = 2, m = + 2〉 Bose-Einstein condensates in a hybrid trap. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:083102. [PMID: 27587095 DOI: 10.1063/1.4960395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present a compact experimental apparatus for Bose-Einstein condensation of (87)Rb in the |F = 2, mF = + 2〉 state. A pre-cooled atomic beam of (87)Rb is obtained by using an unbalanced magneto-optical trap, allowing controlled transfer of trapped atoms from the first vacuum chamber to the science chamber. Here, atoms are transferred to a hybrid trap, as produced by overlapping a magnetic quadrupole trap with a far-detuned optical trap with crossed beam configuration, where forced radiofrequency evaporation is realized. The final evaporation leading to Bose-Einstein condensation is then performed by exponentially lowering the optical trap depth. Control and stabilization systems of the optical trap beams are discussed in detail. The setup reliably produces a pure condensate in the |F = 2, mF = + 2〉 state in 50 s, which includes 33 s loading of the science magneto-optical trap and 17 s forced evaporation.
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Affiliation(s)
- Raffaele Nolli
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Michela Venturelli
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Luca Marmugi
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Arne Wickenbrock
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Ferruccio Renzoni
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Belzig W. Josephson contacts of neutral strongly interacting fermions. Science 2015; 350:1470. [DOI: 10.1126/science.aad6876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Contacts between superconductors are explored via their ultracold atomic gas analogs
[Also see Reports by
Husmann
et al.
and
Valtolina
et al.
]
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Affiliation(s)
- Wolfgang Belzig
- Department of Physics, University of Konstanz, Konstanz, Germany
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